There are four main factors that contribute to iron deficiency in patients with CKD1.
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Iron lost through bleeding can be clinically significant in patients with CKD. It has been estimated that patients on haemodialysis lose 1–3 g of iron per year1. Uraemia-associated platelet dysfunction2, regular phlebotomy, and blood trapping in the dialysis apparatus can all contribute to chronic blood loss1.
Reduced dietary intake
Patients with CKD may have a diet low in iron, either caused by low food intake in general as a result of poor appetite, or due to advice to maintain a low protein diet3.
Inflammation associated with chronic disease can result in iron deficiency. Cytokine-mediated increases in the iron homeostasis hormone hepcidin inhibit mobilisation of iron from iron storage cells, resulting in functional iron deficiency over the short term. Over the longer term, elevated hepcidin can lead to absolute iron deficiency by preventing transport of iron from intestinal enterocytes into the body1. Poor absorption of iron may mean that orally administered iron supplementation is not as effective as IV iron for iron deficiency in patients with inflammation4.
Increased iron requirements during erythropoiesis-stimulating agent (ESA) therapy
ESA therapy is used widely in patients undergoing haemodialysis as a treatment for anaemia. The sudden demand for iron stimulated by ESA-induced erythropoiesis can cause a rapid depletion of iron stores and result in functional or absolute iron deficiency1. Iron deficiency can be a major cause of non-responsiveness to ESA therapy5.
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